The instant invention pertains to the use of simple and complex structures submerged at the surface and at mid water level to attract and aggregate fish. Commercial fishermen in many parts of the world have learned to harvest pelagic fishes that exhibit the tendency to congregate around floating objects such as rafts, logs and other fixed structures. Various studies have been conducted in this area such as: "Attraction of Coastal Pelagic Fishes with Artificial Structures" by Edward S. Klima and Donald A. Witcam, Transactions of the American Fisheries Society, Volume 100, No. 1, January 1971, pp. 86-99; "Association of Fishes with Flotsom in the Off Shore Waters of Central America", John R. Hunter, and Charles T. Mitchell, Fishery Bulletin, Volume 66, No. 1, pp. 13-29; "Anchored Fish Aggregating Devices in Hawaiian Waters", Walter M. Matsumoto, Thomas K. Kazama, and Donald C. Aasted, Marine Fisheries Review, September 1981, pp. 1-13; and "Fields Experiments on the Attraction of Pelagic Fish to Floating Objects", John R. Hunter and Charles T. Mitchell, Bureau of Commercial Fisheries Tuna Resources Laboratory, LaJolla, Calif. "Ecological Significance of a Drifting Object to Pelagic Fishes", Reginald M. Gooding and John Magnuson, Pacific Science, Vol. VVI, No. 4, October 1967, pp. 486-497. The publications are attached to this disclosure and are made a part of it by reference and incorporation.
Research has shown that coastal pelagic fish (i.e., sardines) form aggregations around various structures where they can be harvested with nets. Research has been directed toward determining the feasibility of utilizing submerged artificial objects so that fish can be concentrated in sufficient quantity in the vicinity of these underwater structures in preselected areas so that they could be harvested with various conventional gear. These studies have been conducted in such various areas as the Gulf of Mexico off of the State of Florida, the off shore waters of Costa Rica and the off shore waters of the Hawaiian islands.
Evaluations of artificial floating objects have revealed that more pelagic fish were attracted to three-dimensional structures, than to horizontal or vertical plane surfaces.
The most striking features of these studies are that large quantity of fish associated with the structures throughout the study and that the structures were effective in attracting fish. In one study by Kalima and Wickhman their data showed more than 10,000 fish were estimated to be around each structure. In the Klima and Wickham study data demonstrated that various species had different attraction tendencies to simple and complex structures and their position in the water column.
The Kalima and Wickhman study proported to support the concept that some species may associate with objects in the water as a result of species-specific behavioral mechanisms. The observations of the fish schools could also be explained by schooling companion mechanism. Kilma and Wickhman proposed that floating objects and underwater structures provide spatial references around which fishes can orient in the otherwise unstructured pelagic environment. They further stated that regardless of the mechanism involved the evidence increasingly indicated that the initial attraction is probably the result of a visual stimulus provided by structure in the optical void of the pelagic environment.
The rate of initial attracting was very rapid, indicating the fish could be harvested at frequent intervals. Attraction appeared to be dependent upon the visibility of the structure. A structure's vertical position had some effect on the number of fish attracted. The results of these studies indicate that artificial structures could accumulate coastal pelagic species, a technique that could be incorporated into a commercial harvesting system for this undeveloped aquatic resource.